“WE made incredible mistakes in some crucial moments. Mistakes that killed us.”

Despite amassing a massive 67 per cent of possession, Manchester United managed to go down 3-2 to Brighton as a string of defensive errors proved their undoing.

The Red Devils fielded a near-full strength defence, with left back Luke Shaw arguably the only player deputising — in the absence of injured skipper Antonio Valencia — and yet their frailties at the back saw them let in three goals against a side that last week drew a blank against Watford.

Brighton’s free-scoring first half yielded three strikes from three shots on target, as centre-backs Eric Bailly and Victor Lindelof were singled out for harsh criticism.

Former United star Paul Scholes suggested the latter was at fault for Glenn Murray’s opener.

“I think the bad reaction there is from Lindelof,” he said on BT Sport.

“Once that ball goes into the middle he has to come across and close that space.

“He’s gone [wide] to receive the ball, look how slow he is getting back. He’s even thinking of playing offside there, which is crazy.”

Sky Sports’ Gary Neville also didn’t hold back in his assessment of the pair.

“The centre backs melted and you can’t do that in the Premier League,” former United defender Neville said.

“When Manchester United are so publicly in the transfer window looking for defenders, what belief does that give them?

“They know they’re on borrowed time and I have to say (Eric) Bailly and (Victor) Lindelof were poor. They are the ones Jose has signed.

“It has been poor recruitment. That back four aren’t good enough to win the title. The five centre backs they’ve got are second centre backs. They’re not authoritative or leaders.’

Mourinho’s hunt for a new centre-back monopolised column inches during the recently closed transfer window, as United were linked with a massive range of targets only to finally admit failure with hours remaining on the deadline day clock.

Toby Alderweireld, Harry Maguire, Jerome Boateng, Diego Godin and Yerry Mina were all touted for a move to the Premier League giants as the manager’s patience appeared to wear thin.

Mourinho stated in late July that he “gave a list to my club five names a few months ago” and yet CEO Ed Woodward was unable to complete a deal for a new top line central defender.

This was only the 10th time in Premier League history that Manchester United have conceded three goals in the first half of a match and it’s the first time they’ve done so under Mourinho.

And not even their perennial rescuer, keeper David De Gea, is on hand to save them.

The Spaniard has conceded from 10 of the last 14 shots on target he’s faced in a slump that began during a disappointing World Cup campaign.

Mourinho was desperate to invest in a defender, and against Brighton it wasn’t difficult to see why, but according to ex-England international Jamie Redknapp, the United board should think twice before letting him splash the cash again.

“Lindelof and Bailly have looked like a couple of youth team players, they have looked inexperienced and out of their depth,” Redknapp said on Sky Sports.

“This back four is worth £117m (A$204m). They should be performing so much better.

“How much more money can you throw at the problem?

“He has bought Lindelof and Bailly and they looked so poor today, why would you trust him to spend more money?”

United have a net spend of £302m (A$526m) since Mourinho arrived, and yet his starting centre-back pairing are still capable of making ‘incredible mistakes.’

But as the Portuguese tactician rightfully pointed out in his post-game press conference, “The transfer window opens on January 1,” he said. “It’s closed.”